Mr Rudd said Mr Xi was not expected to attend the World Economic Forum, but suggested his absence from public view was not unusual.

The health and whereabouts of Mr Xi are a mystery.

Mr Xi, who is just weeks away from assuming China’s highest office, is thought to have suffered a serious but not life-threatening stoke. He has not been seen in public since September 1.

The absence of Mr Xi has not been acknowledged by China’s state-run media, and searches of his full name have been blocked on micro-blogging sites. His last name has not been blocked, however, and foreign press articles on his disappearance can be easily accessed within China, despite its often draconian internet censorship.

Late last night a little known Hong Kong magazine, ISUN Affairs, said it had been in contact with a member of Mr Xi’s family, who said he was “healthy".

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It said Mr Xi had been working on reforms and had chosen not to meet any foreign dignitaries.

The magazine said political and economic reform in China would be faster than many expected under Mr Xi’s leadership.

His absence is likely to complicate what has been a messy leadership transition, after the sacking in March of top Communist Party official Bo Xilai, who was removed for “serious disciplinary violations", after the death of British businessman Neil Heywood.

Mr Bo’s wife, Gu Kailai, was later found guilty of murdering the Briton and sentenced to life in prison.

The scandal upset the delicate political balance in Beijing, resulting in an outbreak of factional warfare, as Mr Bo was tipped to win a place on the Standing Committee, the country’s top decision-making body.

Those political issues appear to have been settled in recent weeks, but Mr Xi’s absence from public life could cause them to flare again.

Mr Xi’s elevation is set to happen at the National Party Congress in mid-October, although an official date is yet to be announced.

His disappearance from the political stage has triggered wild speculation about his whereabouts, covering everything from a bad back to an assassination attempt.

His absence became obvious only when a meeting with US Secretary of State
Hillary Clinton
on September 5 was abruptly cancelled. At the time it was widely reported as a snub, but in the days since, Mr Xi’s absence has grown ever more conspicuous.

The health of the country’s top leaders is considered a state secret, although such rumours would usually trigger a hastily arranged public appearance.